This invention relates to a reducible-volume cartridge for holding a viscous substance for use in combination with a dispenser of a pump-type utilizing a vacuum or sub-atmospheric pressure to effect withdrawal of a predetermined amount of the substance from the cartridge for ejection through the dispenser.
One pump-type dispenser relates to syringes for injecting humans or animals with fluids such as serums, vaccines, virus and the like via needles attached to the dispenser. One type is commonly called a pistol grip syringe. This type of syringe fits comfortably in the hand, however, when fully loaded, the syringe is over 16" long, which makes it very user unfriendly when vaccinating animals in tight quarters, such as individual crates or in chutes. If the animal thrashes around, the syringe can get caught up in the bars of the crates or chute and not allow the operator to get his hand out quickly. Refilling the pistol grip syringe is done by inverting the serum bottle, piercing the rubber stopper with the needle on the syringe, and pulling back on the plunger. This causes a vacuum in the syringe tube, thus filling it. Problems with this type syringe dispenser, are that one must hold the bottle and front end of the syringe (needle end) with one hand and pull back the plunger with the other; also, clearing air out of the syringe causes some serum to be expelled as well, which in turn runs down over the syringe, making it very slippery and hard to hold onto. Further, the smaller the needle the harder it becomes to pull the plunger back and bring serum into the syringe. The smaller needle restricts the flow, making the vacuum much more powerful, which in turn fatigues the operator and increases the time it takes to fill the syringe.
When one is hanging onto the needle end during filling and pulling hard on the other end, it is easy to see that one is very prone to a needle stick. Another disadvantage, is that when using this type of syringe with multi-dose vials, the rubber stopper in the vial becomes so perforated with holes that when you invert the bottle, the serum starts to drip out and it is hard to get the needle sealed to enable the vacuum to be formed. Also, bits of the rubber stopper flake off into the needle, which can plug the needle or could be injected into the animal magnifying the possibility of an abscess and/or infection. Every time one uses multi-dose vials, the entire contents of the vial are contaminated every time the pistol grip syringe is refilled. Further, pistol grip syringes are limited to a maximum of 50 cc's of serum within their bodies, which means the problems with refilling are faced repeatedly. Once the syringe is full of serum, one must continually clear the air from the syringe, resulting in serum waste.
Another type of syringe is the "bottle draw off" syringe. This syringe has a mounting surface to hold a bottle in an inverted position. In the center of the mounting surface is a stationary hollow spike which communicates serum with the ejection barrel. Problems with this type of syringe are: every time one pushes the bottle down over the stationary spike, small pieces of rubber flake off and start to restrict the flow of serum, and can eventually completely block the flow of serum. This problem can result in an inadequate does of serum delivered to the animal. When vaccinating with this syringe type, the quick forward movements of the operator will foam the serum making delivery inadequate.
The downward angle that is required for vaccinating, coupled with quick movements can slosh the liquid up to one side of the bottle and away from the hollow spike, resulting in an inadequate amount of serum delivered to the animal. Also, when using multi-dose vials with this syringe, it is easy to see that repeatedly puncturing the rubber stopper with the hollow spike and leaving the vial inverted drastically increases the amount of leakage.
A third type of injecting syringe dispenser is a reservoir draw-off syringe. This syringe has no reservoir of its own but has a long tube hooked to its plunger, and the opposite end is hooked to a reservoir somewhere on the operator's body. This reservoir is usually inverted and carried around the neck, shoulder, or in a pocket. The problems with this type of syringe include: it cannot be used efficiently for smaller vaccinating tasks because the tube alone can only hold 10 ml of serum; it takes much priming to get serum from reservoir out to the end of operator's hand, causing operator fatigue; and the long tube can easily be caught and disconnected from reservoir by surrounding equipment or can be disconnected by surrounding animals.
This syringe suffers some of the same problems as the "bottle draw-off" syringe in that foaming will occur, caused by the quick movements of the operator; and the liquid sloshing away from the exit port will cause air bubbles throughout the entire line and syringe, resulting in inadequate serum being delivered.
Another pump-type dispenser relates to a cartridge of a solid or flexible nature for dispensing a pasty substance, such as toothpaste, lotion, liquid soap and the like through a permanent dispenser normally mounted on the top of the cartridge and utilizing a thumb-pressure dispenser. The main disadvantages of this type of dispenser are the complexity of the pump-dispenser mechanism and the non-re-usability of the cartridge, most if not all being of a disposable nature.
To a solution of these types of problems and disadvantages of the pump-type viscous substancy dispensers of the prior art, this invention is directed.